This invention relates methods of generating and projecting autostereoscopic images.
The quest to produce quality and technically effective three-dimensional images has continued for a number of years. Basically, there are two types of presentation methods or systems that are available for viewing three-dimensional images; these are broadly characterized as either stereoscopic or autostereoscopic.
In stereoscopic systems, pairs of ordinary two-dimensional still photographs or binocular motion pictures are made of an object from two points of view. The two points are separated by a distance equal to the distance between the eyes of a viewer. The pair of photographs or motion pictures are then viewed through a device that allows the right eye to see only the right image and the left eye only the left image. In this viewing system, each eye sees a slightly different image; thereby duplicating the conditions under which the original scene would have been viewed. Consequently, the viewer is aware of only one image that has a three-dimensional effect. Stereoscopic images are typically viewed with special glasses or other viewing equipment that separates what each eye views.
In autostereoscopic systems, it is not necessary for the viewer to wear special glasses or to use any other viewing implement to keep the two images separated. Wherever the observer is seated in a certain area in front of the display, each of his or her eyes will see a different image. Several methods of achieving this effect are known in the art. Past apparatuses of generating and projecting autostereoscopic images have often included multiple projectors and displays. For instance, McLaughlin discloses, in U.S. Pat. No. 5,993,003, a projection system that includes multiple projection systems with multiple CRT displays. This greatly increases the cost of such projection systems. It also increases the amount of room needed to generate the images.
The object of this invention was to create a method of generating and projecting autostereoscopic images that is more compact and less expensive then current methods.
In the preferred embodiments, the system has six major components: an illumination system, a light valve, a relay lens, a beam steering device, projection optics, and a screen assembly.
The illumination system concentrates bright light onto the light valve, as is typical of illumination sources for projector apparatuses of all kinds. The light valve spatially and temporally modulates the intensity of light falling on it, thus creating rapidly changing images. The relay lens magnifies the images and projects them onto a plane or surface within a beam steering device. The beam steering device causes the beam of light exiting from the image to change direction and to be focused so that it enters each of several projection lenses, one after the other in a repeating sequence. The projection lenses, placed in a row in front of the beam steering device, each project a larger version of the image seen in the beam steering device onto a larger screen assembly. The screen assembly, which contains one or more large positive lenses (such as Fresnel lenses), reimages the exit pupil of each of the projection lenses into a different region of space in the area where the observer sits, thus creating viewing zones from within which different images are visible.